Technical Field
The present invention relates to a liquid discharge apparatus and a flexible flat cable.
Related Art
Among liquid discharge apparatuses such as ink jet printers which print images and text by discharging ink, there are liquid discharge apparatuses which use piezoelectric elements (for example, piezo elements). The piezoelectric elements are provided so as to correspond to each of a plurality of discharge sections in a head unit and dots are formed on a medium such as paper by a specific amount of ink (liquid) being discharged from nozzles at specific timings due to the piezoelectric elements being driven in accordance with driving signals. A phenomenon has been confirmed where, although most of the liquid which is discharged lands on the medium and remains on the medium, a portion of the liquid which is discharged may become mist before landing on the medium and is suspended in the air. In addition, another phenomenon has been confirmed where, by being re-suspended due to an air flow which is generated by a carriage which moves above the medium and the medium which is being transported, the liquid which lands on the medium may also become mist before solidified by being absorbed into the medium. The mist which is suspended in this manner becomes attached to various sections inside the casing, but it is particularly easy for the mist to become attached to the surface of a cable which electrically connects an electrical circuit substrate (a main substrate) which is on the main body side and an electrical circuit substrate (a head substrate) which is on the discharge section side which discharges liquid. Examples of reasons for it being easy for the mist to become attached to the surface of the cable are that there are states where it is easy for the mist to become adhered due to a signal line which is provided in the cable transferring driving signals with high voltages, static electricity being generated due to the cable rubbing against various sections inside the casing in liquid discharge apparatuses where the carriage is driven, and the like. The more the liquid discharge apparatus is operated continuously over a long period of time, the mist which becomes adhered to the surface of the cable condenses, forms droplets, and gathers at the end sections of the cable due to vibrations which are generated by the discharge operations and the medium transport operations.
One end of the cable is connected to the head substrate and the other end of the cable is connected to the main substrate as described above, but once attached to the surface of the substrate, it is easy for the liquid to remain at the connection section of the head substrate and the cable due to the positional relationship between the cable and the head substrate. The connection section is not covered for convenience so that the signal line inside the cable and the substrate are electrically connected. Accordingly, when liquid gets into the connection section, an unsuitable electrical connection relationship is established via the liquid between the substrate and the signal line which is provided in the cable and various types of electrical faults including short circuiting are generated. The various types of electrical faults are when high voltages are applied to circuits which operate using low voltages such as logic circuits and when there is short circuiting of a ground line and other various types of signal lines, and there are cases where circuits in inner sections of the head unit are damaged when electrical faults are generated in this manner.
With regard to such problems, Japanese Patent Application Publication No. 2014-4767 discloses a cover member being provided with the objective of preventing ink mist from entering into inner sections of the head unit. In addition, Japanese Patent Application Publication No. 2007-313831 discloses the connection section being sealed in order to prevent liquid becoming attached to electrode sections. In addition, Japanese Patent Application Publication No. 2009-23168 discloses a cable cover section being provided on the head side in order to prevent ink mist from entering into the connection section. In addition, Japanese Unexamined Patent Application Publication No. 2013-248755 discloses an ink absorption layer being provided with the objective of preventing ink mist from entering into inner sections of the head unit.
However, none of the above-cited documents considers the structuring of the connection between the head unit and the cable or configuration of the cable, and there is scope for improvement in order to effectively suppress electrical faults which are caused by liquid which is discharged.